OVC 'Toxic Garden' Helps Identify Plants Deadly to Animals

August 03, 2006 - News Release

Lily-of-the-valley, foxglove and monkshood can all be deadly to pets, livestock and humans. Bleeding heart contains chemicals that can poison cattle. And the common yew tree can cause fatal heart arrhythmia in livestock, dogs and people.

Yet these and other toxic plants are growing in a teaching garden at the Ontario Veterinary College (OVC).

Why would anyone choose to plant these nasty specimens at a veterinary school and hospital? The new OVC “toxic garden” is intended to teach people about common plant species that may be poisonous to animals, said Melanie Philbin, a second-year veterinary student and a member of the Guelph student chapter of the American College of Veterinary Pathologists, which helped spearhead the project.

The students worked with the U of G grounds department to design and landscape the space — located in an isolated, fully enclosed and restricted-access courtyard — and will maintain the garden.

The idea caught on after pathobiology professor Margaret Stalker spoke to the students about the effects of toxic plants. Animals routinely sicken and even die after ingesting various plants in home gardens or farm pastures, and veterinarians are expected to be able to recognize common plant toxicities in various animal species, said Stalker, who is the chapter’s co-mentor along with Prof. Dorothee Bienzle.

Besides opening eyes to the potential hazards in many backyards, the project is designed to teach students about the often-discriminating effects of certain plants. Chokecherry leaves for example, may be toxic to ruminants, but not to dogs or people. And yew whose taxine alkaloids can be fatal for many animals — including horses — is a deer’s tasty meal.

“What’s one animal’s food is another animal’s toxin,” said third-year DVM student Colette Larocque, who is also involved in the project.

The garden includes native Ontario plants — white snakeroot, mayapple, jack-in-the-pulpit — and exotics that have spread as weeds, such as tansy ragwort. There are also garden and forage plants, including rhododendron, clematis, delphinium, day lily and castor bean.

Still to come are another 20 species, including forage crops such as sweet clover. (Stalker points out that Francis Schofield, a longtime OVC pathologist, discovered in the 1920s that mouldy sweet clover could kill cattle.)

The students plans to launch a website with information about the plants ranging from geographic distribution, and habitat and identifying features to toxic principles, susceptible species and clinical signs of intoxication or poisoning. They’ll also place interpretive information about individual species and warning signs in the garden itself.

This information will help everyone from students to clinicians in the Veterinary Teaching Hospital (VTH), said Stalker. “They’re more prepared to make a diagnosis.”

The group has also established connections with the U of G Arboretum — which contains a number of larger and different specimens — and the U of G Herbarium in the College of Biological Science. Also involved in the project is Brent Hoff, a clinicial pathologist and toxicologist with U of G’s Animal Health Laboratory.

Acknowledging concerns about potential hazards to people and animals, Stalker said the garden’s isolated location will help prevent seeds from spreading to other parts of campus, and none of the species is likely to cause inhalant allergies. “It’s an ideal site,” she said, adding that U of G’s Landscape Advisory Committee was also consulted on the project.